package study.corejava.innerclass;

import java.lang.reflect.*;
import java.util.*;

/**
 * This program demonstrates the use of proxies.
 * @version 1.00 2000-04-13
 * @author Cay Horstmann
 */
public class ProxyTest {
	
	public static void main(String[] args) {
		Object[] elements = new Object[1000];

		// fill elements with proxies for the integers 1 ... 1000
		for (int i = 0; i < elements.length; i++) {
			Integer value = i + 1;
			InvocationHandler handler = new TraceHandler(value);
			Object proxy = Proxy.newProxyInstance(null,
					new Class[] { Comparable.class }, handler);
			elements[i] = proxy;
		}

		// construct a random integer
		Integer key = new Random().nextInt(elements.length) + 1;

		// search for the key
		int result = Arrays.binarySearch(elements, key);

		// print match if found
		if (result >= 0)
			System.out.println(elements[result]);
	}
}

/**
 * An invocation handler that prints out the method name and parameters, then
 * invokes the original method
 */
class TraceHandler implements InvocationHandler {
	
	private Object target;

	/**
	 * Constructs a TraceHandler
	 * @param t the implicit parameter of the method call
	 */
	public TraceHandler(Object t) {
		target = t;
	}

	public Object invoke(Object proxy, Method m, Object[] args)
			throws Throwable {
		// print implicit argument
		System.out.print(target);
		// print method name
		System.out.print("." + m.getName() + "(");
		// print explicit arguments
		if (args != null) {
			for (int i = 0; i < args.length; i++) {
				System.out.print(args[i]);
				if (i < args.length - 1)
					System.out.print(", ");
			}
		}
		System.out.println(")");

		// invoke actual method
		return m.invoke(target, args);
	}

}
